The present invention relates to a method and a device for operating an electric machine, in particular of a motor vehicle, said electric machine having a stator with at least one stator winding, wherein the stator winding is supplied with current for setting a demanded torque of the electric machine, wherein a temperature of the stator of the electric machine is detected by means of a temperature sensor, and wherein the current flowing through the stator winding is monitored for performing a plausibility check on the detected temperature.
Furthermore, the present invention relates to a motor vehicle including an electric machine and a device of the aforementioned kind.
Electric machines are increasingly being integrated into the drive train of motor vehicles, in order to generate a drive torque alone or in combination with a conventional internal combustion engine. High demands are being made on the available continuous and peak output of the electric machines, during generator operation as well as during motor operation. The efficiency of the electric drive is also relevant. Generally, the electric drive is operated in a torque control mode, so that a stator winding of the electric machine is supplied with current as a function of a torque demanded of the electric machine. The current which is required for setting the demanded torque is determined as a function of the operating point, via current control.
To monitor the thermal behavior of the electric machine, it is known to provide a temperature sensor which detects the temperature of the stator. Since this is a safety-critical measured variable, it is known to perform a plausibility check on it periodically. For this purpose, the physical relationship between the energy which is introduced into the stator and which is a function of the current flowing through the stator, and the thermal behavior of the stator, is used. If the detected temperature does not change in the case of a significant increase in the introduced energy, the temperature sensor is diagnosed as being defective.